With increasing demand for liquid transportation fuels, decreasing reserves of ‘easy oil’ (crude petroleum oil that can be accessed and recovered easily) and increasing constraints on carbon footprints of such fuels, it is becoming increasingly important to develop routes to produce liquid transportation fuels from biomass in an efficient manner. Such liquid transportation fuels produced from biomass are sometimes also referred to as biofuels. Biomass offers a source of renewable carbon. Therefore, when using such biofuels, it may be possible to achieve more sustainable CO2 emissions over petroleum-derived fuels.
An efficient method for processing biomass into high quality liquid fuels (e.g. diesel fuel and gasoline) is described in WO 2010/117437 A1, in the name of Gas Technology Institute.
Solid feedstocks such as feedstocks containing waste plastics, feedstocks containing lignocellulose (e.g. woody biomass, agricultural residues, forestry residues, residues from the wood products and pulp & paper industries) and municipal solid waste containing lignocellulosic material, waste plastics or food waste are important feedstocks for biomass to fuel processes due to their availability on a large scale. Lignocellulose comprises a mixture of lignin, cellulose and hemicelluloses in any proportion and usually also contains ash and moisture.
Certain conventional hydroconversion catalysts for biomass conversion, similar to those known for refining applications, are used in their sulfided state. In order to form sulfided catalysts, a sulfiding step may be applied to the catalyst once it has been manufactured. In a catalytic process employing fluidized bed reactors, the catalyst may need to be replenished on a regular basis to make up for catalyst losses by attrition. When the catalyst used is sulfided, the sulfiding step is typically done ex-situ. The sulfided form of the catalyst may require careful handling during storage and transport as it is sensitive to air and moisture. The logistics of ex-situ manufacture and transport of sulfided catalyst may therefore require careful attention and review. Most biomass feedstocks (for example, wood) have a low sulfur content (<200 ppmw), and therefore a sulfided catalyst, when used to process biomass, may end up contaminating the hydrocarbon product produced with sulfur leached out from the catalyst.
It would therefore be an advantage to provide a process utilising simpler, more easily produced catalysts. Further, a wider range of catalysts would be adaptable to a broader range of biomass feedstocks for use in the process.